1. Field of the Invention
The present invention relates to a remotely controllable electromagnetic door lock, which uses an electromagnet in addition to a mechanical latch to maintain the door in the locked condition.
2. Introduction and Description of the Prior Art
Security concerns often times require that public access to certain buildings be limited. For example, it is desirable that access to a multi-story apartment building be limited to the tenants, their guests, and other authorized personnel. Tenants and authorized personnel can be supplied with keys. However, it would be very inconvenient for tenants to run to the front door to let their guests into the building each time they are visited by guests. Also, in government facilities it is desirable to allow only those members of the public who have legitimate business to transact within the facility, to be allowed into the facility. For this reason security guards are often used to control admission of members of the public to the facility, and the guards need to be able to allow persons into a building without having to constantly leave their stations. In the above described types of circumstances, the use of remotely operable electric door locks, operated either by tenants from within their apartments or security guards, has become widespread.
U.S. Pat. No. 5,228,730, issued to Gokcebay et al., shows an electric door lock which uses a magnetic latching solenoid to lock and unlock the door. The magnetic latching solenoid changes position in response to a momentarily applied electric current. The Gokcebay et al. device does not use an electromagnet to hold the door closed.
U.S. Pat. No. 5,199,288, issued to Merilainen et al., shows an electric lock which uses an electric motor to move the locking bolt via a worm and gear arrangement. The Merilainen et al. device does not use an electromagnet to hold the door closed.
U.S. Pat. No. 4,073,518, issued to Goodwin, shows an electric door lock which uses solenoids to move locking bars between locked and unlocked positions. The Goodwin device does not use an electromagnet to hold the door closed.
U.S. Pat. No. 3,408,838, issued to Katz, shows an electric door lock which uses an electromagnetic coil to move the door latch and unlock the door. The Katz device does not use an electromagnet to hold the door closed.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.